1. Field of the Invention
The present invention relates to an image forming system, image transmitting apparatus, image data processing method, program, and storage medium.
2. Description of the Related Art
In recent offices, SOHO (Small Office/Home Office) environments, and the like, an MFP (Multi-Functional Peripheral) formed from a copying machine, printer, and scanner, and an SFP (Single-Functional Peripheral) are connected to networks and used.
There are “remote copy” and “BOX delivery” functions of transferring image data between the MFP and the SFP, printing it on a print medium such as paper, and accumulating it in an apparatus. When executing the “remote copy” and “BOX delivery” functions, image data, which is multi-valued luminance data, is transmitted to maintain the reproducibility of tint, particularly for a color image. This is because the luminance density conversion characteristic changes over time, and in actual printing, luminance density conversion processing needs to be done in accordance with the state of the image processing unit.
More specifically, R, G, and B luminance data are converted into C, M, Y, and K (or Bk) density data in accordance with an LUT (Look Up Table) corresponding to the state of the image processing unit. The LUT is updated by executing calibration for correcting a change over time, so the reusability of multi-valued luminance data is high. A dither pattern designed uniquely to the image processing unit is applied to density data to convert the density data into half-tone data. Then, print processing is done.
In terms of the data size, half-tone data is higher in compression efficiency than multi-valued luminance data and multi-valued density data, and can decrease the data size. Thus, half-tone data can have higher response speed in image transfer.
From this, the purpose of use of image data determines which of multi-valued image data having high reusability and half-tone data having high response speed in image transfer is used to transfer an image.
To communicate multi-valued image data and half-tone image data, some facsimile image data transfer techniques have been proposed.
For example, there is proposed a technique when changing the density of image data again after converting image data into half-tone data and transmitting the half-tone data (Japanese Patent Laid-Open No. 3-78370). Japanese Patent Laid-Open No. 3-78370 discloses a method of holding a multi-valued image on the transmitting side, and transmitting half-tone image data having undergone density conversion again in response to a retransmission request from the receiving side.
Japanese Patent Laid-Open No. 2002-27218 proposes a method of determining which of a half-tone image and multi-valued image can be received by the receiving side, and switching an image to be transmitted and transmitting the image, as needed.
As described above, the image data size increases when multi-valued image data is transmitted in “remote copy”. Transfer of image data takes a long time, decreasing the copy speed. In other words, even if remote copy is executed, the transfer destination cannot quickly acquire print data, resulting in a poor-usability system.
If image data processed at a specific half-toning parameter is transmitted to decrease the image data size, poor-reusability image data is transmitted to the receiving side.
Japanese Patent Laid-Open No. 3-78370 proposes a method of holding multi-valued image data on the transmitting side, and transmitting half-tone image data having undergone image processing at a different half-toning parameter in response to a retransmission request from the receiving side.
However, according to Japanese Patent Laid-Open No. 3-78370, the transmitting side needs to hold a multi-valued image as long as it may receive a retransmission request. For image data, the timing of reuse of which is not known, like BOX delivery, the transmitting side needs to hold a multi-valued image for a long time.
Japanese Patent Laid-Open No. 2002-27218 proposes a method of determining which of a half-tone image and multi-valued image can be received by the receiving side, and switching image data to be transmitted.
However, according to Japanese Patent Laid-Open No. 2002-27218, only the image data transmission method is switched in accordance with the ability of the receiving side, and no image data is switched in consideration of the purpose of use of image data.